Du Fu: The war rages on for three months, and a letter from home is worth ten thousand gold.

The Yuefu folk song "Xizhou Song" of the Southern Dynasties has "Recalling that the man has not arrived, I look up to see the flying red."

"Wang Feihong" means looking forward to the letter.

Li Qingzhao's poem cloud: "When the wild geese return, the moon is full on the west tower", "The wild geese are passing by, and I am sad, but they are old acquaintances."

The wild geese have not brought hope. The long-lasting letters aroused the female poet's unrequited lovesickness

For example, "When will the swan geese arrive, there will be abundant autumn water in the rivers and lakes" (Du Fu's "Li Bai is pregnant at the end of the day"), "Shuo Yan's biography is the best, Xiang Huang" Stained with tears" (Li Shangyin's "Lisi") and so on.